Heat oil in a skillet over medium heat. Stir in garlic and onion; cook until soft and slightly browned. Stir in eggplant and sweet potato. Pour about ½ cup of liquid from canned tomatoes. Simmer until juices are absorbed.
Stir in tomatoes, ginger, curry powder, cumin, salt and pepper; simmer until sweet potato begins to soften, about 15 to 20 minutes. (If juices cook off before potatoes are fully cooked, stir in a small amount of water, and cover.)
Place pizza crust on pizza pan. Spread the lentils evenly across the surface of the crust out to the edges. Spread sweet potato mixture evenly on top, and sprinkle with cheese.
Bake in the preheated oven until the edges are browned, about 10 to 13 minutes.